chapter 4 chemical reactions and solutions stoichiometry · 29. in writing the total ionic equation...

CHAPTER 4 Chemical Reactions and Solutions Stoichiometry

61 © Houghton Mifflin Company. All rights reserved.

1. An unknown substance dissolves readily in water but not in benzene (a nonpolar solvent). Molecules of what type are present in the substance?

a) neither polar nor nonpolar

b) polar

c) either polar or nonpolar

d) nonpolar

e) none of these

ANS: b) polar PAGE: 4.1

2. A 20.0-g sample of HF is dissolved in water to give 2.0 102 mL of solution. The concentration of the solution is:

a) 1.0 M

b) 3.0 M

c) 0.10 M

d) 5.0 M

e) 10.0 M

ANS: d) 5.0 M PAGE: 4.3

3. 1.00 mL of a 3.50 10–4 M solution of oleic acid is diluted with 9.00 mL of petroleum ether, forming solution A. 2.00 mL of solution A is diluted with 8.00 mL of petroleum ether, forming solution B. How many grams of oleic acid are 5.00 mL of solution B? (molar mass for oleic acid = 282 g/mol)

a) 4.94 10–4 g

b) 7.00 10–6 g

c) 4.94 10–5 g

d) 1.97 10–6 g

e) 9.87 10–6 g

ANS: e) 9.87 10–6 g PAGE: 4.3

4. How many grams of NaCl are contained in 350. mL of a 0.250 M solution of sodium chloride?

a) 41.7 g

b) 5.11 g

c) 14.6 g

d) 87.5 g

e) none of these

ANS: b) 5.11 g PAGE: 4.3



5. Which of the following aqueous solutions contains the greatest number of ions?

a) 400.0 mL of 0.10 M NaCl

b) 300.0 mL of 0.10 M CaCl2

c) 200.0 mL of 0.10 M FeCl3

d) 200.0 mL of 0.10 M KBr

e) 800.0 mL of 0.10 M sucrose

ANS: b) 300.0 mL of 0.10 M CaCl2 PAGE: 4.3

6. What mass of calcium chloride, CaCl2, is needed to prepare 2.850 L of a 1.56 M solution?

a) 25.9 g

b) 60.8 g

c) 111 g

d) 203 g

e) 493 g

ANS: e) 493 g PAGE: 4.3

7. A 54.8 g sample of SrCl2 is dissolved in 112.5 mL of solution. Calculate the molarity of this solution.

a) 0.346 M

b) 3.07 M

c) 3.96 M

d) 8.89 M

e) none of these

ANS: b) 3.07 M PAGE: 4.3

8. What mass of solute is contained in 256 mL of a 0.895 M ammonium chloride solution?

a) 12.3 g

b) 13.7 g

c) 47.9 g

d) 53.5 g

e) none of these

ANS: a) 12.3 g PAGE: 4.3


© Houghton Mifflin Company. All rights reserved. 63

9. A 51.24-g sample of Ba(OH)2 is dissolved in enough water to make 1.20 liters of solution. How many mL of this solution must be diluted with water in order to make 1.00 liter of 0.100 molar Ba(OH)2?

a) 400. mL

b) 333 mL

c) 278 mL

d) 1.20 103 mL

e) none of these

ANS: a) 400. mL PAGE: 4.3

10. What volume of 18.0 M sulfuric acid must be used to prepare 15.5 L of 0.195 M H2SO4?

a) 168 mL

b) 0.336 L

c) 92.3 mL

d) 226 mL

e) none of these

ANS: a) 168 mL PAGE: 4.3

11. How many grams of NaOH are contained in 5.0 102 mL of a 0.80 M sodium hydroxide solution?

a) 16 g

b) 80. g

c) 20. g

d) 64 g

e) none of these

ANS: a) 16 g PAGE: 4.3

12. A 230.-mL sample of a 0.275 M solution is left on a hot plate overnight; the following morning the solution is 1.10 M. What volume of solvent has evaporated from the 0.275 M solution?

a) 58.0 mL

b) 63.3 mL

c) 172 mL

d) 230. mL

e) 288 mL

ANS: c) 172 mL PAGE: 4.3



13. The net ionic equation for the reaction of aluminum sulfate and sodium hydroxide contains which of the following species?

a) 3Al3+(aq)

b) OH–(aq)

c) 3OH–(aq)

d) 2Al3+(aq)

e) 2Al(OH)3(s)

ANS: c) 3OH–(aq) PAGE: 4.6,8

14. The net ionic equation for the reaction of calcium bromide and sodium phosphate contains which of the following species?

a) Ca2+(aq)

b) PO43–(aq)

c) 2Ca3(PO4)2(s)

d) 6NaBr(aq)

e) 3Ca2+(aq)

ANS: e) 3Ca2+(aq) PAGE: 4.6,8

15. Which of the following is a strong acid?

a) HF

b) KOH

c) HClO4

d) HClO

e) HBrO

ANS: c) HClO4 PAGE: 4.2

16. All of the following are weak acids except

a) HCNO

b) HBr

c) HF

d) HNO2

e) HCN

ANS: b) HBr PAGE: 4.2



17. Which of the following is not a strong base?

a) Ca(OH)2

b) KOH

c) NH3

d) LiOH

e) Sr(OH)2

ANS: c) NH3 PAGE: 4.2

18. Which of the following is paired incorrectly?

a) HI – strong acid

b) HNO3 – weak acid

c) Ba(OH)2 – strong base

d) HBr – strong acid

e) NH3 – weak acid

ANS: b) HNO3 – weak acid PAGE: 4.2

19. The interaction between solute particles and water molecules, which tends to cause a salt to fall apart in water, is called

a) hydration.

b) polarization.

c) dispersion.

d) coagulation.

e) conductivity.

ANS: a) hydration PAGE: 4.1

20. Consider two organic molecules, ethanol and benzene. One dissolves in water and the other does not. Why?

a) They have different molar masses.

b) One is ionic, the other is not.

c) One is an electrolyte, the other is not.

d) Ethanol contains a polar O—H bond, and benzene does not.

e) Two of these.

ANS: d) Ethanol contains a polar O—H bond, and benzene does not. PAGE: 4.1,2



21. When sodium chloride and lead(II) nitrate react in an aqueous solution, which of the following terms will be present in the balanced molecular equation?

a) PbCl(s)

b) Pb2Cl(s)

c) NaNO3(aq)

d) 2NaNO3(aq)

e) 2PbCl2(s)

ANS: d) 2NaNO3(aq) PAGE: 4.5,6

22. When solutions of phosphoric acid and iron(III) nitrate react, which of the following terms will be present in the balanced molecular equation?

a) HNO3(aq)

b) 3HNO3(aq)

c) 2FePO4(s)

d) 3FePO4(s)

e) 2HNO3(aq)

ANS: b) 3HNO3(aq) PAGE: 4.5,6

23. When solutions of cobalt(II) chloride and carbonic acid react, which of the following terms will be present in the net ionic equation?

a) CoCO3(s)

b) H+(aq)

c) 2CoCO3(s)

d) 2Cl–(aq)

e) two of these

ANS: a) CoCO3(s) PAGE: 4.5,6

24. You have exposed electrodes of a light bulb in a solution of H2SO4 such that the light bulb is on. You add a dilute solution and the bulb grows dim. Which of the following could be in the solution?

a) Ba(OH)2

b) NaNO3

c) K2SO4

d) Ca(NO3)2

e) none of these

ANS: a) Ba(OH)2 PAGE: 4.2,5,8



25. You mix 260. mL of 1.20 M lead(II) nitrate with 300. mL of 1.90 M potassium iodide. The lead(II) iodide is insoluble. Which of the following is false?

a) The final concentration of Pb2+ ions is 0.0482 M.

b) You form 131 g of lead(II) iodide.

c) The final concentration of K+ is 1.02 M.

d) The final concentration of NO3- is 1.02 M.

e) All are true.

ANS: d) The final concentration of NO3- is 1.02 M. PAGE: 4.5-7

26. The concentration of a salt water solution which sits in an open beaker decreases over time.

ANS: False PAGE: 4.3

27. You have 2 solutions of chemical A. To determine which has the highest concentration of A in molarity, what is the minimum number of the following you must know?

I. the mass in grams of A in each solution

II. the molar mass of A

III. the volume of water added to each solution

IV. the total volume of the solution

a) 0

b) 1

c) 2

d) 3

e) You must know all of them.

ANS: c) 2 PAGE: 4.3

28. The following reactions:

Pb2+ + 2I– PbI2

2Ce4+ + 2I– I2 + 2Ce3+

HOAc + NH3 NH4+ + OAc–

are examples of

a) acid-base reactions.

b) unbalanced reactions.

c) precipitation, acid-base, and redox reactions, respectively.

d) redox, acid-base, and precipitation reactions, respectively.

e) precipitation, redox, and acid-base reactions, respectively.

ANS: e) precipitation, redox, and acid-base reactions, respectively. PAGE: 4.4-9



29. In writing the total ionic equation for the reaction (if any) that occurs when aqueous solutions of KOH and Mg(NO3)2 are mixed, which of the following would not be written as ionic species?

a) KOH

b) Mg(NO3)2

c) Mg(OH)2

d) KNO3

e) All of these would be written as ionic species.

ANS: c) Mg(OH)2 PAGE: 4.4,6

30–32. Aqueous solutions of barium chloride and silver nitrate are mixed to form solid silver chloride and aqueous barium nitrate.

30. The balanced molecular equation contains which one of the following terms?

a) AgCl(s)

b) 2AgCl(s)

c) 2Ba(NO3)2

d) BaNO3

e) 3AgCl(s)

ANS: b) 2AgCl(s) PAGE: 4.5,6

31. The balanced complete ionic equation contains which of the following terms?

a) 2Ba2+(aq)

b) Cl–(aq)

c) 2Ag+(aq)

d) NO3 – (aq)

e) 3NO3 – (aq)

ANS: c) 2Ag+(aq) PAGE: 4.5,6

32. The net ionic equation contains which of the following terms?

a) Ag+(aq)

b) Ba2+(aq)

c) NO3 – (aq)

d) 2NO3 – (aq)

e) none of these

ANS: a) Ag+(aq) PAGE: 4.5,6



33. The man who discovered the essential nature of acids through solution conductivity studies is

a) Priestly.

b) Boyle.

c) Einstein.

d) Mendeleev.

e) Arrhenius.

ANS: e) Arrhenius. PAGE: 4.2

34. The following reactions

2K(s) + Br2(l) 2KBr(s)

AgNO3(aq) + NaCl(aq) AgCl(s) + NaNO3(aq)

HCl(aq) + KOH(aq) H2O(l) + KCl(aq)

are examples of

a) precipitation reactions.

b) redox, precipitation, and acid-base, respectively.

c) precipitation (two) and acid-base reactions, respectively.

d) redox reactions.

e) none of these

ANS: b) redox, precipitation, and acid-base, respectively. PAGE: 4.4–9

35. Aqueous solutions of sodium sulfide and copper(II) chloride are mixed together. Which statement is correct?

a) Both NaCl and CuS precipitate from solution.

b) No precipitate forms.

c) CuS will precipitate from solution.

d) NaCl will precipitate from solution.

e) No reaction will occur.

ANS: c) CuS will precipitate from solution. PAGE: 4.5

36. Which of the following salts is insoluble in water?

a) Na2S

b) K3PO4

c) Pb(NO3)2

d) CaCl2

e) All of these are soluble in water.

ANS: e) All of these are soluble in water. PAGE: 4.5



37. How many of the following salts are expected to be insoluble in water?

sodium sulfide barium nitrate ammonium sulfate potassium phosphate

a) none

b) 1

c) 2

d) 3

e) 4

ANS: a) none PAGE: 4.5

38. When NH3(aq) is added to Cu2+(aq), a precipitate initially forms. Its formula is:

a) Cu(NH3)2+4

b) Cu(NO3)2

c) Cu(OH)2

d) Cu(NH3)2+2

e) CuO

ANS: c) Cu(OH)2 PAGE: 4.5

39. Which of the following ions is most likely to form an insoluble sulfate?

a) K+

b) Li+

c) Ca2+

d) S2–

e) Cl–

ANS: c) Ca2+ PAGE: 4.5

40. Which of the following compounds is soluble in water?

a) Ni(OH)2

b) K3PO4

c) BaSO4

d) CoCO3

e) PbCl2

ANS: b) K3PO4 PAGE: 4.5



41. A solution contains the ions Ag+, Pb2+, and Ni2+. Dilute solutions of NaCl, Na2SO4, and Na2S are available to separate the positive ions from each other. In order to effect separation, the solutions should be added in which order?

a) Na2SO4, NaCl, Na2S

b) Na2SO4, Na2S, NaCl

c) Na2S, NaCl, Na2SO4

d) NaCl, Na2S, Na2SO4

e) NaCl, Na2SO4, Na2S

ANS: a) Na2SO4, NaCl, Na2S PAGE: 4.5

42. Which pair of ions would not be expected to form a precipitate when dilute solutions of each are mixed?

a) Al3+, S2–

b) Pb2+, Cl–

c) Ba2+, PO3–4

d) Pb2+, OH–

e) Mg2+, SO2–4

ANS: e) Mg2+, SO2–4 PAGE: 4.5

43. In the balanced molecular equation for the neutralization of sodium hydroxide with sulfuric acid, the products are:

a) NaSO4 + H2O

b) NaSO3 + 2H2O

c) 2NaSO4 + H2O

d) Na2S + 2H2O

e) Na2SO4 + 2H2O

ANS: e) Na2SO4 + 2H2O PAGE: 4.6,8

44. If all of the chloride in a 5.000-g sample of an unknown metal chloride is precipitated as AgCl with 70.90 mL of 0.2010 M AgNO3, what is the percentage of chloride in the sample?

a) 50.55%

b) 10.10%

c) 1.425%

d) 20.22%

e) none of these

ANS: b) 10.10% PAGE: 4.7



45. Which of the following do you need to know to be able to calculate the molarity of a salt solution?

I. the mass of salt added

II. the molar mass of the salt

III. the volume of water added

IV. the total volume of the solution

a) I, III

b) I, II, III

c) II, III

d) I, II, IV

e) You need all of the information.

ANS: d) I, II, IV PAGE: 4.3

46. You mix 60.0 mL of 1.0 M silver nitrate with 25.0 mL of 0.80 M sodium chloride. What mass of silver chloride should you form?

a) 2.9 g

b) 5.8 g

c) 8.7 g

d) 9.6 g

e) none of these

ANS: a) 2.9 g PAGE: 4.7

47. You have separate solutions of HCl and H2SO4 with the same concentrations in terms of molarity. You wish to neutralize a solution of NaOH. Which acid solution would require more volume (in mL) to neutralize the base?

a) the HCl solution

b) the H2SO4 solution

c) You need to know the acid concentrations to answer this question.

d) You need to know the volume and concentration of the NaOH solution to answer this question.

e) c and d

ANS: a) the HCl solution PAGE: 4.8

48. What mass of NaOH is required to react exactly with 25.0 mL of 1.2 M H2SO4?

a) 1.2 g

b) 1.8 g

c) 2.4 g

d) 3.5 g

e) none of these

ANS: c) 2.4 g PAGE: 4.8



49. A 3.00-g sample of an alloy (containing only Pb and Sn) was dissolved in nitric acid (HNO3). Sulfuric acid was added to this solution, which precipitated 2.93 g of PbSO4. Assuming that all of the lead was precipitated, what is the percentage of Sn in the sample? (molar mass of PbSO4 = 303.3 g/mol)

a) 33.3% Sn

b) 17.7% Sn

c) 50.0% Sn

d) 66.7% Sn

e) 2.00% Sn

ANS: a) 33.3% Sn PAGE: 4.7

50. A mixture contained no fluorine compound except methyl fluoroacetate, FCH2COOCH3 (molar mass = 92.1 g/mol. When chemically treated, all the fluorine was converted to CaF2 (molar mass = 78.1 g/mol). The mass of CaF2 obtained was 12.1 g. Find the mass of methyl fluoroacetate in the original mixture.

a) 92.0 g

b) 28.5 g

c) 24.2 g

d) 14.3 g

e) 12.1 g

ANS: b) 28.5 g PAGE: 4.7

51. A 1.000-g sample of a metal chloride, MCl2, is dissolved in water and treated with excess aqueous silver nitrate. The silver chloride that formed weighed 1.286 g. Calculate the atomic mass of M.

a) 222.8 g

b) 76.00 g

c) 152.0 g

d) 304.0 g

e) none of these

ANS: c) 152.0 g PAGE: 4.7

52-55. You have 75.0 mL of a 2.50 M solution of Na2CrO4(aq). You also have 125 mL of a 2.50 M solution of AgNO3(aq). Calculate the concentrations of the following ions when the two solutions are added together.

52. Na+

a) 0 M

b) 0.938 M

c) 1.88 M

d) 2.50 M

e) 5.00 M

ANS: c) 1.88 M PAGE: 4.7



53. CrO42-

a) 0 M

b) 0.156 M

c) 0.188 M

d) 0.938 M

e) 2.50 M

ANS: b) 0.156 M PAGE: 4.7

54. Ag+

a) 0 M

b) 0.800 M

c) 1.00 M

d) 1.50 M

e) 1.80 M

ANS: a) 0 M PAGE: 4.7

55. NO3-

a) 0 M

b) 0.313 M

c) 1.56 M

d) 3.13 M

e) 2.50 M

ANS: c) 1.56 M PAGE: 4.7

56. A 0.307-g sample of an unknown triprotic acid is titrated to the third equivalence point using 35.2 mL of 0.106 M NaOH. Calculate the molar mass of the acid.

a) 247 g/mol

b) 171 g/mol

c) 165 g/mol

d) 151 g/mol

e) 82.7 g/mol

ANS: a) 247 g/mol PAGE: 4.8



57. Sulfamic acid, HSO3NH2 (molar mass = 97.1 g/mol), is a strong monoprotic acid that can be used to standardize a strong base:

HSO3NH2(aq) + KOH(aq) KSO2NH2(aq) + H2O(l)

A 0.179-g sample of HSO3NH2 required 19.4 mL of an aqueous solution of KOH for complete reaction. What is the molarity of the KOH solution?

a) 9.25 M

b) 9.50 10–5 M

c) 0.0950 M

d) 0.194 M

e) none of these

ANS: c) 0.0950 M PAGE: 4.8

58. A student weighs out 0.568 g of KHP (molar mass = 204 g/mol) and titrates to the equivalence point with 36.78 mL of a stock NaOH solution. What is the concentration of the stock NaOH solution? KHP is an acid with one acidic proton.

a) 0.100 M

b) 3.15 M

c) 0.943 M

d) 0.0757 M

e) none of these

ANS: d) 0.0757 M PAGE: 4.8

59. In which of the following does nitrogen have an oxidation state of +4?

a) HNO3

b) NO2

c) N2O

d) NH4Cl

e) NaNO2

ANS: b) NO2 PAGE: 4.9

60. Which of the following statements is not true?

a) When a metal reacts with a nonmetal, an ionic compound is formed.

b) A metal-nonmetal reaction can always be assumed to be an oxidation-reduction reaction.

c) Two nonmetals can undergo an oxidation-reduction reaction.

d) When two nonmetals react, the compound formed is ionic.

e) A metal-nonmetal reaction involves electron transfer.

ANS: d) When two nonmetals react, the compound formed is ionic. PAGE: 4.9



61. The following reactions

ZnBr2(aq) + 2AgNO3(aq) Zn(NO3)2(aq) + 2AgBr(s)

KBr(aq) + AgNO3(aq) AgBr(s) + KNO3(aq)

are examples of

a) oxidation-reduction reactions.

b) acid-base reactions.

c) precipitation reactions.

d) a and c

e) none of these

ANS: c) precipitation reactions. PAGE: 4.4-9

62. All of the following reactions

2Al(s) + 3Br2(l) 2AlBr3(s)

2Ag2O(s) 4Ag(s) + O2(g)

CH4(l) + 2O2(g) CO2(g) + 2H2O(g)

can be classified as

a) oxidation-reduction reactions.

b) combustion reactions.

c) precipitation reactions.

d) a and b

e) a and c

ANS: a) oxidation-reduction reactions. PAGE: 4.4-9

63. In the reaction 2Ca(s) + O2(g) 2CaO(s), which species is oxidized?

a) O2

b) O2–

c) Ca

d) Ca2+

e) none of these

ANS: c) Ca PAGE: 4.9

64. In the reaction 2Cs(s) + Cl2(g) 2CsCl(s), Cl2 is

a) the reducing agent.

b) the oxidizing agent.

c) oxidized.

d) the electron donor.

e) two of these

ANS: b) the oxidizing agent. PAGE: 4.9



65. In the reaction N2(g) + 3H2(g) 2NH3(g), N2 is

a) oxidized.

b) reduced.

c) the electron donor.

d) the reducing agent.

e) two of these

ANS: b) reduced. PAGE: 4.9

66. In the reaction P4(s) + 10Cl2(g) 4PCl5(s), the reducing agent is

a) chlorine.

b) PCl5.

c) phosphorus.

d) Cl–.

e) none of these

ANS: c) phosphorus. PAGE: 4.9

67. In the reaction C(s) + O2(g) CO2(g) carbon is __________.

a) the reducing agent

b) the electron acceptor

c) reduced

d) the oxidizing agent

e) more than one of these

ANS: a) the reducing agent PAGE: 4.9

68. Diabetics often need injections of insulin to help maintain the proper blood glucose levels in their bodies. How many moles of insulin are needed to make up 45 mL of 0.0052 M insulin solution?

a) 4.6 10–4 mol

b) 5.0 10–3 mol

c) 1.7 10–4 mol

d) 6.0 102 mol

e) 2.3 10–4 mol

ANS: e) 2.3 10–4 mol PAGE: 4.3



69. For the reaction of sodium bromide with chlorine gas to form sodium chloride and bromine, the appropriate half-reactions are (ox = oxidation and re = reduction):

a) ox: Cl2 + 2e– 2Cl–; re: 2Br– Br2 + 2e–

b) ox: 2Br– Br2 + 2e–; re: Cl2 + 2e– 2Cl–

c) ox: Cl + e– Cl–; re: Br Br– + e–

d) ox: Br + 2e– Br2–; re: 2Cl– Cl2 + 2e–

e) ox: 2Na+ + 2e– 2Na; re: 2Cl– Cl2 + 2e–

ANS: b) ox: 2Br– Br2 + 2e–; re: Cl2 + 2e– 2Cl– PAGE: 4.10

70. Which of the following reactions does not involve oxidation-reduction?

a) CH4 + 3O2 2H2O + CO2

b) Zn + 2HCl ZnCl2 + H2

c) 2Na + 2H2O 2NaOH + H2

d) MnO2 + 4HCl Cl2 + 2H2O + MnCl2

e) All are oxidation-reduction reactions.

ANS: e) All are oxidation-reduction reactions. PAGE: 4.9

71. Which of the following are oxidation-reduction reactions?

I. PCl3 + Cl2 PCl5

II. Cu + 2AgNO3 Cu(NO3)2 + 2Ag

III. CO2 + 2LiOH Li2CO3 + H2O

IV. FeCl2 + 2NaOH Fe(OH)2 + 2NaCl

a) III

b) IV

c) I and II

d) I, II, and III

e) I, II, III, and IV

ANS: c) I and II PAGE: 4.9

72. Which of the following statements is(are) true? Oxidation and reduction

a) cannot occur independently of each other.

b) accompany all chemical changes.

c) describe the loss and gain of electron(s), respectively.

d) result in a change in the oxidation states of the species involved.

e) a, c, and d are true

ANS: e) a, c, and d are true PAGE: 4.9



73. In the reaction Zn + H2SO4 ZnSO4 + H2, which, if any, element is oxidized?

a) zinc

b) hydrogen

c) sulfur

d) oxygen

e) none of these

ANS: a) zinc PAGE: 4.9

74. In the following reaction, which species is oxidized?

8NaI + 5H2SO4 4I2 + H2S + 4Na2SO4 + 4H2O

a) sodium

b) iodine

c) sulfur

d) hydrogen

e) oxygen

ANS: b) iodine PAGE: 4.9

75. How many of the following are oxidation-reduction reactions?

NaOH + HCl NaCl + H2O

Cu + 2AgNO3 2Ag + Cu(NO3)2

Mg(OH)2 MgO + H2O

N2 + 3H2 2NH3

a) 0

b) 1

c) 2

d) 3

e) 4

ANS: c) 2 PAGE: 4.9

76. In the reaction shown below, what species is oxidized?

2NaI + Br2 2NaBr + I2

a) Na+

b) I–

c) Br2

d) Br–

e) I2

ANS: b) I– PAGE: 4.9



77. Given the following reaction in acidic media:

Fe2+ + Cr2O72– Fe3+ + Cr3+

answer the following question: The coefficient for water in the balanced reaction is

a) 1.

b) 3.

c) 5.

d) 7.

e) none of these

ANS: d) 7 PAGE: 4.10

78. Balance the following oxidation-reduction reaction using the half-reaction method:

Fe3+ + I– Fe2+ + I2

In the balanced equation, the coefficient of Fe2+ is

a) 1.

b) 2.

c) 3.

d) 4.

e) none of these

ANS: b) 2 PAGE: 4.10

79. The following unbalanced equation represents a reaction that occurs in basic solution:

MnO42– + C2O4

2– MnO2 + CO32–

How many moles of MnO42– are required to produce 1 mole of CO3

2–?

a) 4

b) 3

c) 2

d) 1

e) none of these

ANS: e) none of these PAGE: 4.10



80–82. The following reaction occurs in aqueous acid solution:

NO3– + I– IO3– + NO2

80. The oxidation state of iodine in IO3– is:

a) 0

b) +3

c) –3

d) +5

e) –5

ANS: d) +5 PAGE: 4.9

81. In the balanced equation the coefficient of NO3– is:

a) 2

b) 3

c) 4

d) 5

e) 6

ANS: e) 6 PAGE: 4.10

82. In the balanced equation the coefficient of water is:

a) 1

b) 2

c) 3

d) 4

e) 5

ANS: c) 3 PAGE: 4.10

83. When the equation Cl2 Cl– + ClO3– (basic solution) is balanced using the smallest

whole-number coefficients, the coefficient of OH– is:

a) 1

b) 2

c) 3

d) 4

e) 6

ANS: e) 6 PAGE: 4.10



84. When the following reaction is balanced in acidic solution, what is the coefficient of I2?

IO3– + I– I2

a) 1

b) 2

c) 3

d) 4

e) none of these

ANS: c) 3 PAGE: 4.10

85. The MnO4– is often used to analyze for the Fe2+ content of an aqueous solution via the

reaction MnO4– + Fe2+ Fe3+ + Mn2+ in acidic solution. What is the ratio of MnO4

– :

Fe2+ in the balanced equation?

a) 1 : 1 b) 2 : 1 c) 3 : 1 d) 4 : 1 e) 5 : 1

ANS: e) 5 : 1 PAGE: 4.10

86. Balance the following oxidation–reduction reaction using the half-reaction method.

Cr2O72– + I2 Cr3+ + IO3

–

In the balanced equation, the coefficient of water is:

a) 4 b) 17 c) 11 d) 7 e) 6

ANS: b) 17 PAGE: 4.10

87. With what volume of 5.0 M HF will 7.4 g of calcium hydroxide react completely, according to the reaction 2HF + Ca(OH)2 CaF2 + 2H2O?

a) 20. mL

b) 50. mL

c) 30. mL

d) 40. mL

e) 1.0 102 mL

ANS: d) 40. mL PAGE: 4.8



88. For the redox reaction 2Fe2+ + Cl2 2Fe3+ + 6Cl– which of the following are the correct half-reactions?

I. Cl2 + 2e– 2Cl–

II. Cl Cl– + e–

III. Cl2 2Cl– + 2e–

IV. Fe2+ Fe3+ + e–

V. Fe2+ + e– Fe3+

a) I and IV b) I and V c) II and IV d) II and V e) III and IV

ANS: a) I and IV PAGE: 4.10

89. The following equation describes the oxidation of ethanol to acetic acid by potassium permanganate:

3C2H5OH + 4KMnO4 3HC2H3O2 + 4MnO2 + 4KOH + H2O

5.0 g of ethanol and an excess of aqueous KMnO4 are reacted, and 5.9 g HC2H3O2 result. What is the percent yield?

a) 100%

b) 91%

c) 67%

d) 30.%

e) 5.9 g HC2H3O2 is impossible since it represents more than a 100% yield.

ANS: b) 91% PAGE: 3.9,4.10

90. Given the reaction

2MnO4– + 5H2O2 + 6H+ 2Mn2+ + 8H2O + 5O2

determine the number of electrons involved in this reaction.

a) 10

b) 8

c) 6

d) 4

e) 2

ANS: a) 10 PAGE: 4.10



Selecting from the following reagents, indicate which reagents would be mixed to give the compounds in the questions below.

CuSO4(aq) Fe2(CO3)3(s) NH3(aq)

CuCO3(s) FeCl3(aq) Na2SO4(aq)

Cr(OH)3(s) H2SO4(aq)

91. Cu(OH)2

ANS: CuSO4(aq) and NH3(aq) PAGE: 4.5,6

92. FeCl3(aq) + Na2SO4(aq)

ANS: FeCl3(aq) + Na2SO4(aq) PAGE: 4.5,6

Write balanced equations for each of the processes in the questions below, choosing from the following substances as reactants:

BaCl2 O2 H2SO4 HNO3

C2H5OH H2O Ca(OH)2 K

Na2CrO4 KOH Pb(NO3)2

93. Precipitation of BaSO4 from solution

ANS: H2SO4 + BaCl2 BaSO4 + 2HCl PAGE: 4.5,9

94. Formation of hydrogen gas

ANS: 2K + H2O 2KOH + H2 PAGE: 4.5,9

95. Neutralization of sulfuric acid

ANS: H2SO4 + 2KOH K2SO4 + 2H2O PAGE: 4.5,9

96. Combustion reaction

ANS: C2H5OH + 3O2 2CO2 + 3H2O PAGE: 4.5,9

97. Dissolution of calcium hydroxide with another reagent

ANS: Ca(OH)2 + 2HCl CaCl2 + 2H2O PAGE: 4.5,9

98–103. Balance each of the following equations.

98. C3H5(NO3)3 N2 + CO2 + H2O + O2

ANS: 4C3H5(NO3)3 6N2 + 12CO2 + 10H2O + O2 PAGE: 4.10

99. KI + HNO3 KNO3 + NO + I2 + H2O

ANS: 6KI + 8HNO3 6KNO3 + 2NO + 3I2 + 4H2O PAGE: 4.10

100. Cr2O72– + I– Cr3+ + IO3

– (acid)

ANS: 8H+ + Cr2O72– + I– 2Cr3+ + IO3

– + 4H2O PAGE: 4.10



101. Zn + As2O3 AsH3 + Zn2+ (acid)

ANS: 12H+ + 6Zn + As2O3 2AsH3 + 6Zn2+ + 3H2O PAGE: 4.10

102. MnO4– + Br– MnO2 + BrO3

– (base)

ANS: H2O + 2MnO4– + Br– 2MnO2 + BrO3

– + 2OH– PAGE: 4.10

103. Bi(OH)3 + SnO22– Bi + SnO3

2– (base)

ANS: 2Bi(OH)3 + 3SnO22– 2Bi + 3SnO3

2– + 3H2O PAGE: 4.10

104. Polar molecules have an unequal distribution of charge within the molecule.

ANS: True PAGE: 4.1

105. An acid is a substance that produces OH– ions in water.


106. The filtrate is the solid formed when two solutions are mixed.


107. A chemical that changes color at the endpoint of a reaction is called a colorimeter.


108. Oxidation is the gain of electrons.


109. A reducing agent is an electron donor.

ANS: True PAGE: 4.9

110. A molecule with an unequal charge distribution is said to be a(n) __________ molecule.

ANS: polar PAGE: 4.1

111. Soluble ionic compounds containing the hydroxide ion are called strong __________.

ANS: bases PAGE: 4.1

112. A(n) __________ is a substance dissolved in a liquid to make a solution.

ANS: solute PAGE: 4.2

113. A(n) __________ electrolyte dissociates to a great extent in an aqueous solution.

ANS: strong PAGE: 4.2

114. Molarity is defined as __________ of solute per volume of solution in ___________.

ANS: moles, liters PAGE: 4.6

chapter 4 chemical reactions and solutions stoichiometry · 29. in writing the total ionic equation...

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